Generally, pigments have the strong cohesion force, which presents us with problems regarding the hue and dispersability in utilizing them as colorants. In order to solve the problems, most pigments are surface-treated in advance. As surface-treatment-agents for pigments, there are known, for example, salts of rosin with calcium and barium, and those of fatty acids with calcium and barium, and the like. Nevertheless, they suffer from disadvantages, such as their limited application scope in terms of pigments to be treated, poor processability and unsatisfactory chroma and brightness of resultant pigments.